Method of simultaneously boarding and setting knitted hosiery

ABSTRACT

A KNITTED FABRIC HAVING A MATRIX OF INTERCONNECTED SPANDEX YARNS, SUCH AS CIRCULAR KNIT WOMEN&#39;&#39;S HOSIERY, CONTAINING SPANDEX AND NYLON YARNS HAVING INTERCONNECTED LOOPS, IS BOARDED TO THE FINAL SHAPE FOR THE HOSERY AND MADE NON-RUN WITHOUT AFFECTING ANY OF THE OTHER PROPERTIES OF THE FABRIC OR HOSIERY BY BEING PLACED UNDER TENSION AND SUBJECTED TO SUPERHEATED STEAM AT A TEMPERATURE IN THE RANGE OF 340*F. TO 380*F.FOR A TIME SUFFICIENT TO FUSE THE INTERCONNECTED LOOPS OF THE SPANDEX YARN AND TO SET THE HOSIERY IN ITS FINAL SHAPE.

W. E. ALDRICH 1972 METHOD. OF SIMULTANEOUSLY BOARDING AND SETTING KNITTED HOSIERY Filed Aug. 17, 1970 INVENTOR.

Will/AM ALDRICH BY ITTQR VIYS United States Patent 3,705,066 METHOD OF SIMULTANEOUSLY BOARDING AND SETTING KNITTED HOSIERY William E. Aldrich, Cranston, R.I., assiguor to Warnaco Inc., Bridgeport, Conn. Filed Aug. 17, 1970, Ser. No. 64,422 Int. Cl. D04b 39/00 U.S. Cl. 156-148 11 Claims ABSTRACT OF THE DISCLOSURE A knitted fabric having a matrix of interconnected spandex yarns, such as circular knit womens hosiery, containing spandex and nylon yarns having interconnected loops, is boarded to the final shape for the hosiery and made non-run without affecting any of the other properties of the fabric or hosiery by being placed under tension and subjected to superheated steam at a temperature in the range of 340 F. to 380 F. for a time sufficient to fuse the interconnected loops of the spandex yarn and to set the hosiery in its final shape.

The present invention relates generally to a method of treating a knitted fabric containing spandex and in particular to a process for simultaneously boarding and setting knitted hosiery containing a spandex yarn having interconnected loops.

Throughout the years substantial efforts have been made in womens hosiery products to render the same substantially run-proof. In a typical hosiery fabric, yarns of synthetic and/or natural fibers are knitted together on a circular knitting machine, With the particular yarns being subjected to a wide degree of choice depending upon the desired ultimate properties for the particular hosiery product. Thus various combinations of synthetic yarns such as rayon, nylon, orlon acrylon, dacron, spandex and the like have been knitted alone or together with natural fibers, such as cotton, wool, silk, and the like in various stitch configurations. With the advent of spandex, which is a long-chain synthetic polymer containing approximately 85% or more of segmented polyurethane, there has been considerable interest in spandex-containing hosiery since spandex is particularly suited to impact elasticity to such knitted fabrics. One such hosiery fabric includes a matrix of interconnected spandex yarns with a body yarn of nylon knitted in a manner to have the requisite stretch and power performance for such stretch or elastic hosiery.

Further, throughout the years, various approaches and methods have been suggested to impart non-run characteristics to fabrics including womens hosiery which fabrics consist in whole or in part of thermoplastic synthetic yarns. Such methods involve the welding together of the yarns at the crossover parts or points to preclude the occurrence of runs or ladders. For example, in British Pat. No. 901,172, published July 18, 1962, there is disclosed a method for simultaneously boarding and imparting nonrun characteristics to nylon hosiery in which fusion at the crossover points is achieved by the use of high frequency dielectric heating. This is achieved in a manner such that the heat generated in the fabric is concentrated at the yarn crossover points of the fabric and the temperature of the yarn at such crossover poins is raised to the 3,705,066 Patented Dec. 5, 1972 point where the crossover points are welded together without affecting the properties of the hosiery such as loss of hand, discoloration, etc. Additionally this British patent suggests that, in the event of undesirable loss of elasticity in the hose as a result of fusion at the crossover points, additional stretch or elasticity can be introduced into the final hosiery product by initially employing the then available stretch or crimped yarns.

More recently, in British Pat. No. 1,176,789, published on Jan. 7, 1970, which is based upon US. application Ser. No. 634,535 filed Apr. 28, 1967 (now U.S. Pat. No. 3,578,546 of May 11, 1971), there is disclosed a non-run fabric, typically of a matrix of interconnected spandex yarns having a yarn of a different material (i.e., nylon) incorporated into the matrix, with the matrix fused at only the interconnected spandex yarns. The fusion technique of this British patent is stated to be based upon the discovery that if spandex yarn is linked to spandex yarn under tension and the fabric is heated, the spandex yarn junctions will fuse at a temperature far below the melting point of spandex (about 446 F.). Accordingly, the process of this patent involves knitting a hosiery blank with spandex yarn loops engaging spandex yarn loops in every wale and course of the fabric, stretching the fabric so that the spandex yarns forming each loop are firmly held in contact with the spandex yarn of each adjacent loop and then while the fabric is so stretched placing the fabric in an autoclave and introducing steam at a temperature within the range of 230 F. to 290 F. for up to 30 minutes.

For the reasons which are well understood to those skilled in the textile and hosiery arts, the foregoing techniques are not particularly suited to the requirements for mass production manufacture of hosiery at relatively low unit cost. For example, the autoclave technique for setting the cross-over points described in the recent British patent is impractical for production purposes due to the relatively long residence time for the boarded hosiery in the autoclave. Although this residence time could be substantially reduced, as by increasing the temperature, such increases in temperature bring about a substantial increase in pressure and require specialized high-pressure equipment and the introduction of safeguards to minimize industrial hazard. Indeed, in many states and municipalities, there are special regulations as to use of such highpressure equipment.

Broadly, it is an object of the present invention to provide an improved method for rendering a spandex-containing knitted hosiery fabric non-run which obviates one or more of the foregoing difiiculties. Specifically, it is within the contemplation of the present invention to provide a method of simultaneously boarding and setting knitted hosiery containing a spandex yarn which is highly practical for commercial production, is completely compatible with existing hosiery-processing techniques, represents substantially no industrial hazard, and utilizes readily available commercial equipment.

In accordance with an illustrative embodiment demonstrating objects and features of the present invention, my method of treating a knitted fabric having a matrix of interconnected spandex yarns to fuse the same includes the steps of subjecting the knitted fabric to superheated steam at a temperature in the range of 340 F. to 380 F. for a time in excess of two minutes and less than five minutes to fuse the spandex yarns at the interconnections thereof. More particularly, the present method can be practiced in a manner to simultaneously board and set circular knit hosiery such that incident to a single operation substantially comparable to conventional boarding, the hosiery blank may be boarded to the final shape and have non-run characteristics imparted thereto. Advantageously, the present process is not only compatible with existing hosiery-processing techniques but is readily practiced on the commercial basis due to the usual availability of an in-plant capability producing steam for superheating. Uniform fusing of the hosiery is achieved in relative short residence times (i.e., 2 minutes as compared to time suggested in the prior art) and the temperatures involved are in the range of the sticking temperature for spandex which is far below the melting point and any temperature at which degradation of the fabric and/or discoloration occurs.

The above brief description as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description, when considered in conjunction with the accompanying drawing wherein:

FIG. 1 is an elevational view with parts broken away, of a typical apparatus for processing circular knit womens hosiery in accordance with the present invention; and

FIG. 2 is a side elevational view, with parts broken away, showing internal details of the equipment.

Referring now specifically to the drawings, there is shown typical apparatus generally designated by the reference numeral for processing womens hosiery H in accordance with the present invention. Such apparatus which may be specially designed or modified from existing equipment includes a processing chest 12 which receives the hosiery H which is loaded on one or more forms 16 at the loading station 14. As is generally understood, the forms 16 are mounted on a carrier 18 which is supported on a rail 20 such that the loaded hosiery H may be moved from the loading station 14 into chest 12 through access door 22 provided at the side of chest 12 facing the loading station 14.

The processing chest 12 may be of any one of number of constructions including that which is illustrated wherein the chest includes insulated top wall 24, bottom wall 26, side walls 28 and 30, and rear wall 32. Electrical heaters generally designated as 36 are embedded in the walls of chest 12 in heat transfer relation to the interior 34 of the chest. Heaters 36 may be set at the appropriate temperatures to establish the desired temperature within the interior or chamber 34 of chest 12 by thermostatic control 38 (see FIG. 1). Provision is made for the introduction of superheated steam into chamber 34 as by steam pipe 40 connected to plural distribution pipes 42, 44 within the chamber. It will be appreciated that the positioning of the steam pipes 42, 44 is illustrative and that this position may vary and that baffles may be provided to insure proper distribution and circulation of the live steam throughout the entire processing chamber 34.

Provision is made for introducing air into the processing chamber 34, as by blower 46 which includes an inlet 46a open to the atmosphere or ambient air and an outlet 46b which passes through the upper wall 24 of the chest 12 for introducing air into chamber 34. Provision is also made for the exit of air from processing chamber 34 as by exhaust pipe 48 and one or more water traps 50 are provided in the bottom wall of the chest to remove the products of condensation. Apparatus of this general type is available for conventional pre-boarding and finishing of hosiery from a number of resources, including the Turbo Machine Company of Lansdale, Pa., and one such typical apparatus as is described in that companys brochure entitled Turbo Superset Pre-Boarder.

In actual use, the circular knit hosiery H is loaded on to the form 16 at the form-loading station 14 with the shape and size of the forms being selected in relation to the hosiery blanks to place the hosiery fabric under tension for subsequent processing to render the same non-run. The loaded hosiery is then introduced into the processing chest 12 through door 22 and the requisite processing conditions are established within the chamber 34 to subject the boarded hosiery H to superheated steam at a temperature in the range of 340 F. to 380 F. for a time in excess of two minutes and preferably less than five minutes to fuse the interconnected loops of the spandex yarn and to set the hosiery H in its final shape.

The spandex yarn is under tension during the exposure to superheated steam such that each stitch pulls against itself at the crossover points of the stitches. The exposure to superheated steam under the conditions described quickly softens the spandex yarn to cause fusion or welding at the crossover points, thereby rendering the hosiery fabric substantially non-run while setting the hosiery to its final shape. It will be appreciated that this is accomplished in relatively short processing times in a manner basically compatible with regular hosiery processing techniques and indeed is achieved concurrent with the conventional boarding step and may be practiced on a commercial basis with relatively simple and inexpensive equip ment.

A latitude of modification, change and substitution is intended in the foregoing disclosure and in certain instances some features of the invention will be used without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be constructed broadly and in a manner consistent with the spirit and scope of the present invention.

What I claim is:

1. A method of treating a knitted fabric having a matrix of interconnected spandex yarns to fuse said interconnected spandex yarns comprising the steps of subjecting said knitted fabric to superheated steam at a temperature in the range of 340 F. to 380 F. for a time in excess of two minutes and less than five minutes to fuse said interconnected spandex yarns at the interconnections thereof.

2. A method according to claim 1 wherein said temperature is in the range of 350 F. to 360 F.

3. A method according to claim 1 wherein said time is less than three minutes.

4. A method of simultaneously boarding and setting knitted hosiery containing a spandex yarn having interconnected loops comprising the steps of knitting a hosiery blank containing said spandex yarn having interconnected loops, placing said blank on a board of the final shape for said hosiery to tension said interconnected loops and subjecting the boarded blank to superheated steam at a temperature in the range of 340 F. to 380 F. for a time sufficient to fuse said interconnected loops of said hosiery blank to each other at crossing points thereof to thereby introduce a non-run characteristic in said hosiery and to set the same in said final shape.

5. The method according to claim 4 wherein said time is from three to five minutes.

6. The method according to claim 5 wherein a yarn of a different material is incorporated in a matrix with said spandex yarn during the knitting of said hosiery blank.

7. The method according to claim 6 wherein the yarn of a different material is of nylon.

8. A method of treating a knitted fabric having a matrix of interconnected spandex yarns and a yarn of a diiferent material incorporated into said matrix to fuse said interconnected spandex yarns comprising the steps of subjecting said fabric to superheated steam at a temperature in the range of 340 F. to 380 F. for a time in excess of two minutes and less than five minutes to fuse said interconnected spandex yarns.

9. A method according to claim 8 wherein said temperature is in the range of 350 F. to 360 F.

5 6 10. A method according to claim 8 wherein said time 3,286,490 11/1966 Martin 66172 R is less than three minutes. 3,315,328 4/ 1967 Ibrahim 66202 X 11. A method according to claim 10 wherein said yarn 3,329,757 7/1967 Johnson 264282 of a different material is nylon. 3,387,448 6/ 1968 Lathem et a1. 66202 X 5 References Cited ROBERT F. BURNETT, Primary Examiner UNITED STATES PATENTS R. L. MAY, Assistant Examiner 3,578,546 5/1971 Morancy 66202 X 3,069,883 12/1962 Burleson et a1 66202 X 3,069,885 12/1962 Cooper et a1. 66202 X 10 66202; 156-161, 181,306 

